Nemertea is a phylum of invertebrate animals also known as ribbon worms or proboscis worms. Most of the 1,400 or so species are marine, with a few living in fresh water and a small number of terrestrial forms; they are found in all marine habits, and throughout the world's oceans. Nemerteans are named after Nemertes, one of the Nereids of Greek mythology, and alternative spellings for the phylum have included Nemertini and Nemertinea. Libbie Hyman named them Rhynchocoela, a name used primarily in North America but gradually abandoned since the 1980s.
The earliest record of a nemertean worm is probably an account by Olaus Magnus in 1555 of a long, greyish-blue marine worm, which is probably Lineus longissimus, but the first species was not formally described until Gunnerus described the same species (as Ascaris longissima) in 1770. In 1995, a total of 1,149 species had been described and grouped into 250 genera.
Ecology and distribution
The majority of nemertean worms live on or in the sea floor, with many species extending into brackish water in estuaries, and some freshwater or fully terrestrial species. They are often found in and among seaweeds, rocks, mussel and barnacle beds, or buried in mud, sand, or gravel substrates. Freshwater genera include the large genus Prostoma, while the terrestrial forms are best represented by Geonemertes, a genus mostly found in Australasia, but with one species in the Seychelles, one found widely across the Indo-Pacific, one from Tristan da Cunha in the South Atlantic, and one, G. chalicophora, first found in the Palmengarten in Frankfurt, but since discovered in the Canary Islands, Madeira and the Azores.
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